Function pqPipelineProcessQueue

src/interfaces/libpq/fe-exec.c:3035–3093

* pqPipelineProcessQueue: subroutine for PQgetResult * In pipeline mode, start processing the results of the next query in the queue. */

 *		In pipeline mode, start processing the results of the next query in the queue.
 */
static void
pqPipelineProcessQueue(PGconn *conn)
{
	switch (conn->asyncStatus)
	{
		case PGASYNC_COPY_IN:
		case PGASYNC_COPY_OUT:
		case PGASYNC_COPY_BOTH:
		case PGASYNC_READY:
		case PGASYNC_READY_MORE:
		case PGASYNC_BUSY:
			/* client still has to process current query or results */
			return;
		case PGASYNC_IDLE:
			/* next query please */
			break;
	}

	/* Nothing to do if not in pipeline mode, or queue is empty */
	if (conn->pipelineStatus == PQ_PIPELINE_OFF ||
		conn->cmd_queue_head == NULL)
		return;

	/* Initialize async result-accumulation state */
	pqClearAsyncResult(conn);

	/*
	 * Reset single-row processing mode.  (Client has to set it up for each
	 * query, if desired.)
	 */
	conn->singleRowMode = false;

	if (conn->pipelineStatus == PQ_PIPELINE_ABORTED &&
		conn->cmd_queue_head->queryclass != PGQUERY_SYNC)
	{
		/*
		 * In an aborted pipeline we don't get anything from the server for
		 * each result; we're just discarding commands from the queue until we
		 * get to the next sync from the server.
		 *
		 * The PGRES_PIPELINE_ABORTED results tell the client that its queries
		 * got aborted.
		 */
		conn->result = PQmakeEmptyPGresult(conn, PGRES_PIPELINE_ABORTED);
		if (!conn->result)
		{
			appendPQExpBufferStr(&conn->errorMessage,
								 libpq_gettext("out of memory\n"));
			pqSaveErrorResult(conn);
			return;
		}
		conn->asyncStatus = PGASYNC_READY;
	}
	else
	{
		/* allow parsing to continue */
		conn->asyncStatus = PGASYNC_BUSY;
	}